Perimeter security system
- Thread starter bobmiller
- Start date
Not to be funny, but do you want to come visit or do you want the history in an .xls?
A simplistic burg panel does not have the intelligence, even with cross zoning, to be able to effectively discriminate a false alarm on outdoor detection circuits. I've installed hundreds of full bore systems on very high risk sites and flight lines that far exceed what most pay for a car, not to mention the design specification is to have 100% coverage with pattern overlap.
This is some of the stuff I put in:
http://catalogs.infocommiq.com/avcat/images/documents/brochure/GBRLiterature.pdf
A simplistic burg panel does not have the intelligence, even with cross zoning, to be able to effectively discriminate a false alarm on outdoor detection circuits. I've installed hundreds of full bore systems on very high risk sites and flight lines that far exceed what most pay for a car, not to mention the design specification is to have 100% coverage with pattern overlap.
This is some of the stuff I put in:
http://catalogs.infocommiq.com/avcat/images/documents/brochure/GBRLiterature.pdf
I am not worried about alarm panel intelligence. A simple contact AND circuit is easy enough for a first year electrician apprentice to wire.
Your experience should make you quite qualified to answer that simple question.
Form the little I have seen with these cheap MS units, wind causing sudden temperature changes seems to be the major cause of false triggers. What do you think the chances of two units false triggering when facing opposite directions about 10m apart?
Your experience should make you quite qualified to answer that simple question.
Form the little I have seen with these cheap MS units, wind causing sudden temperature changes seems to be the major cause of false triggers. What do you think the chances of two units false triggering when facing opposite directions about 10m apart?
NeverDie
Senior Member
Are there pressure sensors that can be mounted below the soil surface? It would only catch footsteps that are close enough to it, but I would imagine it's also unlikely to false alarm?
I have some buried soil moisture sensors and, interestingly, they register when someone steps on the ground above them. I wouldn't utilize them for an alarm system though, because as-built the updates are too infrequent, among other reasons.
I have some buried soil moisture sensors and, interestingly, they register when someone steps on the ground above them. I wouldn't utilize them for an alarm system though, because as-built the updates are too infrequent, among other reasons.
@ Larry, the wiring is not the issue, the detection circuits false at some point or another. Without getting into the design and build of the system and other specifics and discounting a "simple" installation of a pair of contacts:
Each sensor is DEOLR, surged and opto-isolated. Shields also bonded. They are also linked via logic on an access control system and have very specific items and conditionals written to mitigate the false alarms as much as possible. We had their engineers visit the site when false alarms were deemed an issue prior to writing the logic and programming the panels to inhibit as many falses as possible. Everything is 100% dead nuts or +/- 2% tolerance (which is unheard of on installations normally). There are no temperature issues (silicone heating pads installed) and frosting or other enviromental is not an issue. The units are within fenced open topped exhibits and the bird immunity is active and tested. The units false at some point or another with no pattern or weather explanation (though snow does sink the IR signature down).
@ Never: Pressure is not what is used, it is referred to as a "leaky coax" or ported coax system. Very labor intensive to install and adjust and also subject to false alarms depending on the installed enviroment. Sometimes just as bad as a MW or PE based system.
Each sensor is DEOLR, surged and opto-isolated. Shields also bonded. They are also linked via logic on an access control system and have very specific items and conditionals written to mitigate the false alarms as much as possible. We had their engineers visit the site when false alarms were deemed an issue prior to writing the logic and programming the panels to inhibit as many falses as possible. Everything is 100% dead nuts or +/- 2% tolerance (which is unheard of on installations normally). There are no temperature issues (silicone heating pads installed) and frosting or other enviromental is not an issue. The units are within fenced open topped exhibits and the bird immunity is active and tested. The units false at some point or another with no pattern or weather explanation (though snow does sink the IR signature down).
@ Never: Pressure is not what is used, it is referred to as a "leaky coax" or ported coax system. Very labor intensive to install and adjust and also subject to false alarms depending on the installed enviroment. Sometimes just as bad as a MW or PE based system.
@ Larry, I never said that, you're confusing what you want to hear with what was said by myself. Your suggestion will not work fine and will not mitigate or lessen a false alarm. Your example is no different than how beam tower pairs are installed.
Outdoor sensors, even those wired in parallel or via cross zone pairs will false, it's just a matter of when. As I said, the install I referenced has multiple units installed in that exact same manner and the result is the same with a lot of back end logic and discrimination.
Outdoor sensors, even those wired in parallel or via cross zone pairs will false, it's just a matter of when. As I said, the install I referenced has multiple units installed in that exact same manner and the result is the same with a lot of back end logic and discrimination.
I just drew a conclusion from you, as an expert, not answering the simple question posed twice.
You did tell me how your systems and units are complex and reliable but stated nothing about the topic or addressed the concept indicating, to me, you didn't understand it or didn't read it. Telling me they fault rarely indicates the concept should work just fine.
You did tell me how your systems and units are complex and reliable but stated nothing about the topic or addressed the concept indicating, to me, you didn't understand it or didn't read it. Telling me they fault rarely indicates the concept should work just fine.
NeverDie
Senior Member
I remember when I visited the nuclear missle museum in Tucson, Arizona (where you can see an actual nuclear missle silo and command center from roughly the 1960's era), in those days they had a chain link fence around the permieter, and IIRC they had some kind of really big horn microwave motion detector for alerting the missle crew to intruders. It was big enough that it looked like it could double as some kind of powerful weapon (and who knows, maybe it did), but more likely it was just state-of-the-art for that era.
pete_c
Guru
A bit more on big microwave looking antennas.
Long Range Acoustic Device
Not so much for detection you can DIY a small perimeter LRAD for less than $100.
It works so well that you have to search for the DIY's on the internet (well not hidden though). They are there.
Avoidance of the sound works; continued long term exposure will cause damage to the auditory apparatus, nausa, vomiting, et al.
Short term exposure will causing some ringing and deafness for maybe a day or so.
Think of it as a 140 dB ultrasonic sound horn (you can't hear it; you just feel it). (you can do wide or narrow sound dispersion).
Thinking years ago it was just referred to as an (acoustic) pain field generator.
Long Range Acoustic Device
Not so much for detection you can DIY a small perimeter LRAD for less than $100.
It works so well that you have to search for the DIY's on the internet (well not hidden though). They are there.
Avoidance of the sound works; continued long term exposure will cause damage to the auditory apparatus, nausa, vomiting, et al.
Short term exposure will causing some ringing and deafness for maybe a day or so.
Think of it as a 140 dB ultrasonic sound horn (you can't hear it; you just feel it). (you can do wide or narrow sound dispersion).
Thinking years ago it was just referred to as an (acoustic) pain field generator.
False, actually, I chose to ignore the elementary summary of installation methodology that was referenced in post #18. A monkey can make a series or parallel connection with any device and not understand why it's a good or bad idea. Apologies, I didn't see an actual question posted twice by yourself. Your first post was a very simplistic summary of how a cross zone pair or pool works and already exists. It is a band-aid for system design and false alarms and should really not be used a basis of design for a system.LarrylLix said:
There is no guideline as to what generates a false in relation to the detector itself....it can be environmental or a physical item and it's not limited to a simplistic view of a particular technology over another, such as PIR sections always false while MW does not or PE's work fine but PIR's false. Outdoor system have a very high false incident rate, period. There it is spelled out. If you want reliability and a less falses while maintaining performance and the ability to actually determine a valid signal compared to a false, it's not going to happen with any number of detectors installed in parallel or series until you get into a larger layered system and start tracking the movements between items that trigger and then work on signatures and patterns with analytics.
A pair of detectors increases the likelyhood of a false if you don't have back ended logic and a clear layered system design. It'll also decrease the overall sensitivity and effectiveness of the system as a whole. Wired in parallel, then you have twice the amount of variables that generate an actual alarm condition with half the ability to discriminate.
An alarm panel, even those with cross zoning, do not have the intelligence to effectively be connected to an outdoor detection circuit for anything other than basic annunciation functionality. In the case of cross zoning, in the event of a trouble being reported (when the first zone trips) it may not be possible to discriminate which detector generated the initial knock on the zone pool, and forget about this if you wire detectors in parallel.
NeverDie
Senior Member
If I could use it to vanish the squirrels that like to gnaw on my house, it would be worth the $100. It looks like you have to aim it though, so I guess you'd need to automate the aiming as well?pete_c said:
I looked it up, and that Titan missle base used dopler radar for detecting intruders. Here's a photo:
pete_c
Guru
No.
You can do wide dispersion of sound locally. Have a look at basic speaker tweeter methodologies. (long range too can be cylinders bonded together or parabolic focused using the cylinders as the horns). Multiples arranged for widest dispersion.
Unrelated to sound played with white (bluish) light early Cree lamps and they did literally cause night blindness if you looked at them. 1 watt white light versus warm lighting. Actually sort of piecing and bad for the retina; especially at night.
